PREPARED BY R.A.ARUL RAJA ASSISTANT PROFESSOR SRM UNIVERSITY BASIC MECHANICAL ENGINEERING PREPARED BY R.A.ARUL RAJA ASSISTANT PROFESSOR SRM UNIVERSITY

MACHINE ELEMENTS

SPRINGS Spring is an elastic body which deflects to certain position when force is applied and it recovers its original shape when the force is released

TYPES OF SPRINGS Hellical spring Conical and volute springs Torsion spring Spiral spring Leaf spring

HELLICAL SPRING TYPES Compression hellical spring (open coiled) Tension hellical spring (closed coiled)

Compression helical spring (open coiled)

Tension hellical spring (closed coiled)

In open coiled hellical springs the spring wire is coiled in such a way that there is a large gap between two consecutive turns In closed coiled hellical springs the spring wire is coiled so close such a way that there is no gap between two consecutive turns

TENSION HELICAL SPRING (OR) CLOSED COILED SPRING It has some means of transferring the load from the support to the body by means of some arrangement. It stretches apart to create load. The gap between the successive coils is small. The wire is coiled in a sequence that the turn is at right angles to the axis of the spring. The spring is loaded along the axis. By applying load the spring elongates in action

CONICAL AND VOLUTE SPRINGS These springs are used in special applications. Here the number of active coils gradually decreases

TORSION SPRINGS If the load given is torsional load then the spring is called as torsion springs.

TORSION SPRING It is also a form of helical spring, but it rotates about an axis to create load. It releases the load in an arc around the axis. Mainly used for torque transmission The ends of the spring are attached to other application objects, so that if the object rotates around the center of the spring, it tends to push the spring to retrieve its normal position.

SPIRAL SPRING It is made of a band of steel wrapped around itself a number of times to create a geometric shape. Its inner end is attached to an arbor and outer end is attached to a retaining drum. It has a few rotations and also contains a thicker band of steel. It releases power when it unwinds.

LEAF SPRING

LEAF SPRING It consists of number of flat plates of varying lengths held together by means of clamps and bolts. These springs are mostly used in automobiles.

SPRING MATERIALS The mainly used material for manufacturing the springs are as follows: Hard drawn high carbon steel. 9)Chrome vanadium. Oil tempered high carbon steel. 10) Chrome silicon. Stainless steel Copper or nickel based alloys. Phosphor bronze. Inconel. Monel Titanium.

Kequivalent-when springs are in series

Kequivalent-when springs are in parallel (Δ1= Δ2)

COMBINED SYSTEM (BOTH SERIES AND PARALLEL)

APPLICATIONS OF SPRINGS To apply forces and controlling motion, as in brakes and clutches. Measuring forces, as in the case of a spring balance. Storing energy, as in the case of springs used in watches and toys. Reducing the effect of shocks and vibrations in vehicles and machine foundations.

SPRING NOMENCLATURE

Solid length= nxd n= total no. of coils d= diameter of wire Free length= Solid length + max. compression+ clearance (max 1 mm)

SPRING INDEX: D/d D=mean diameter of the coil d=diameter of wire SPRING RATE (stiffness): K=F/δ F= Load applied δ= deflection of spring Pitch= Distance between two adjacent coils in uncompressed state

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